Abstract: Composer William Duckworth’s piano cycle The Time Curve Preludes (1979) is considered to be the first work in a style called “postminimalism.” In the intervening years, postminimalism has become a popular compositional style. Even the most famous of the early minimalists, Steve Reich and Philip Glass, have written music that more closely resembles postminimalism than their earlier styles. In this thesis, I examine The Time Curve Preludes to gain insights into postminimalism. In Part 1, I focus on the two traits commonly cited in scholarly and critical literature that differentiate postminimalism from minimalism: the diminished audibility and presence of a strict, and a greater focus on expressivity. In Part 2, I analyze three of the preludes to demonstrate how they exemplify postminimalism and to offer insights into their construction. These analyses reveal how Duckworth manipulates and disguises familiar minimalist tropes that were hitherto known for their transparency, such as phase-shifting (Prelude 6) and additive processes (Prelude 14), by embellishing, rotating, and otherwise altering short melodic patterns.